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ID Date Author Type Categoryup Subject
  10659   Fri Oct 31 19:59:26 2014 KojiUpdateGeneralSome locking work / PRMI analysis

Preparations

- According to Diego's report, the MC WFS gains were too high. We'll fix this later by tweaking the servo shapes.
But for now, all of the WFS gains were reduced by 40%.
i.e. WFS(1|2)(PIT|YAW) gains from 5 to 3, MC2TRANS(PIT|YAW) gains from 50 to 30.

- Aligned IMC carefully and ran the offset nulling script. MC REFL became 0.435~0.445 and MC TRANS was ~16600.

- Locked the arms and ran ASS.


PRMI

- Started locking PRMI. I just used REFL33I&Q as suggested by the configure script. The PRMI locking was not so robust.
Particularly, the third violin mode of PRM and BS seemed to get excited and dominated the signals.
I modified Vio3 filter in the violin filter for BS and PRM to include zero at 1921Hz where the growing peak was seen.

- We probably want to start from the 1f signals for DRMI lock acquisition. So I wanted to check how REFL11s are.
Measured the demod phase and relative gain between 33I and 11I. (By the way, REFL11I whitening gain was lowered to 0dB).
REFL11I had about x10 gain and the same phase compared to REFL33I. The demod phase for REFL11 was +21deg.
Also checked REFL55 phase and gain. 55Q has almost the same gain as 33Q. And the adjusted phase was 25deg.
These were just rough adjustment of the demod phases.

- Then the servo configuration was transtioned to Configuration 1 (below), and then Configuration 2.

- This configuration was very stable and the PRMI stayed locked about ~1 hour. During this long lock, I could measure 
PSDs, sensing matrix, and etc. Also I could play with the PRM ASC. I wasn't sure if the POP is actually stabilized or not.
(I have no data)

- I noticed that something was ringinging up at 1883Hz. Another 3rd order viloin mode???

- The lock was lost due to too strong injection. But also it reacquired without touching.

- Precise demod phase adjustment has been done by elliminating PRCL from the Q signals.

REFL11 16.75
REFL33 133.0
REFL55 31.0
REFL165 -142 
AS55 -53

- Configiration1 (REFL11I&REFL55Q)

REFL11: WTN 0dB PHASE 21deg, REFL11I x0.1 -> PRCL
REFL33: WTN 30dB PHASE 145deg
REFL55: WTN 21dB PHASE 25deg, REFL55Q x1 -> MICH

PRCL: GAIN -0.04 FM4/5 ON, Triggered FM 2/3/6/9, Servo trigger: POP22I 50up 10down, No Normaization.
MICH: GAIN 10 FM4/5 ON, Triggered FM 2/3/6/9, Servo trigger: POP22I 50up 10down, No Normaization.

PRCL -> PRM +1
MICH -> PRM -0.2625, BS +0.50 BS

- Configuration 2 (REFL11I&Q)

Same as above except:
REFL11Q x-0.1 -> MICH


Calibration

Let's use these entries 

PRM: http://nodus.ligo.caltech.edu:8080/40m/8255
PRM:  (19.6 +/- 0.3) x 10^{-9} (Hz/f)^2 m/counts

BS/ITMs http://nodus.ligo.caltech.edu:8080/40m/8242
BS     = (20.7 +/- 0.1)    x 10 -9 / f2
ITMX = (4.70 +/- 0.02)  x 10 -9/ f2
ITMY = (4.66 +/- 0.02) x 10 -9/ f2

- PRCL Calibration

Lockin oscillator module 675.13Hz 100 -> +1 PRM

Measurement bandwidth 0.1Hz -> Signal power BW 0.471232 (FLATTOP window)

C1:SUS-PRM_LSC_IN1: 118.99 cnt/rtHz => 5.12pm/rtHz
REFL11I: 17.84  cnt/rtHz => 3.49e12 cnt/m
REFL33I:  2.28  cnt/rtHz => 4.46e11 cnt/m
REFL55I:  0.158 cnt/rtHz => 3.09e10 cnt/m
REFL165I: 1.63  cnt/rtHz => 3.19e11 cnt/m


- MICH Calibration

Lockin oscillator module 675.13Hz 100 -> -1 ITMX +1 ITMY

Measurement bandwidth 0.1Hz -> Signal power BW 0.471232 (FLATTOP window)

C1:SUS-ITMX_LSC_IN1: 121.79 cnt/rtHz => 1.26pm/rtHz
C1:SUS-ITMY_LSC_IN1: 121.79 cnt/rtHz => 1.25pm/rtHz
REFL11Q:  0.0329   cnt/rtHz => 1.32e10 cnt/m (PRCL/MICH ratio 265)
REFL33Q:  0.00773  cnt/rtHz => 3.09e9  cnt/m (144)
REFL55Q:  0.001645 cnt/rtHz => 6.58e8  cnt/m (47)
REFL165Q: 0.00374  cnt/rtHz => 1.50e9  cnt/m (213) !?
AS55Q:    0.0696   cnt/rtHz => 2.78e10 cnt/m

Openloop TF measurements
Servo filter TF measuremnts

The UGFs were ~250Hz for PRCL and ~120Hz for MICH, respectively.
The OLTF was modelled by the servo and violin filters TF from foton, estimated TF of the AA/AI filters, and the constant time delay.

Displacement spectra measurement

SELF NOTE: DON'T FORGET TO TURN ON the whitening of the unused signals! (USE MC DOF or manual switch)

- PRCL

The PRCL displacement was measured with REFL I signals. In the attachment 3, the in-loop and free-run equivalent displacements are shown (red and blue).
Other out-of-loop sensors (33/55/165) were also plotted together.

FIrst of all, the uncompensated displacement noise level of PRCL is around 1e-7 m/rtHz. This is a good indication that the calibration was not crazy.

The sensing noise of REFL11 seems to be 1e-15~1e-16 m/rtHz at high frequency which is enough for now.
As expected, REFL11I has the best noise level among the REFLs. At low frequency, it seemed that the noise level is limited by something at 1e-12 m/rtHz.
Of course, we can't say this is just the sensing noise of the other REFLs or the noise of the REFL11I. But this noise level is enough small for the locking of
the low finesse (F<100) PRCL cavity.

Remembering we had no trouble locking PRCL with REFL33/55/165, this plot indicates that the PRCL was suppressed too much below 2Hz.
And we want more supression between 5Hz to 30Hz. We have resonant gains in ther PRCL servo but not sure how effective they were.
If we consider the contamination of PRCL in MICH, we should try to optimize the PRCL servo.

- MICH

The MICH displacement was similary calibrated to PRCL. The signal sources were the REFL Qs and AS55Q.
In the attachment 4, the in-loop and free-run equivalent displacements are shown (red and blue).
Other out-of-loop sensors were also plotted together.

The problem here is that the out-of-loop levels (REFL33/55/165 and AS55) show almost the same levels
and thus it is likely that the actual (out-of-loop) stability of MICH is this kind of level. If we believe it, we only have
~1/100 supression between 1-10Hz and ~1/10Hz below 0.5Hz.
The strong servo control does nothing to stablize
MICH. From the out-of-loop noise level of MICH, this comes for the contamination from leakage PRCL.
We really need to improve the signal quality of MICH.

The MICH servo filter has quite complicated shape, but is not necessary according to the estimated free-runing MICH.

The MICH free-running motion is quieter than the PRCL one between 1Hz to 30Hz. The reasonable explanation is
that it comes from poor vibration isolation of the tip-tilts. It means that SRCL also has the similar noise level to PRCL.

Attachment 1: PRMIsb_PRCL_OLTF.pdf
PRMIsb_PRCL_OLTF.pdf
Attachment 2: PRMIsb_MICH_OLTF.pdf
PRMIsb_MICH_OLTF.pdf
Attachment 3: PRMIsb_PRCL_SPE.pdf
PRMIsb_PRCL_SPE.pdf
Attachment 4: PRMIsb_MICH_SPE.pdf
PRMIsb_MICH_SPE.pdf
  10670   Wed Nov 5 11:37:29 2014 manasaUpdateGeneralLight from Y end reaches PSL table

[Steve, Diego, Manasa]

Since the beatnotes have disappeared, I am taking this as a chance to put the FOL setup together hoping it might help us find them.

Two 70m long fibers now run along the length of the Y arm and reach the PSL table.

The fibers are running through armaflex insulating tubes on the cable racks. The excess length ~6m sits in its spool on the top of the PSL table enclosure.

Both the fibers were tested OK using the fiber fault locator. We had to remove the coupled end of the fiber from the mount and put it back in the process. So there is only 8mW of end laser power at the PSL table after this activity as opposed to ~13mW.  This will be recovered with some alignment tweaking.

After the activity I found that the ETMY wouldn't damp. I traced the problem to the ETMY SUS model not running in c1iscey. Restarting the models in c1iscey solved the problem.

 

  10671   Wed Nov 5 17:50:29 2014 manasaUpdateGeneralPSL and AUXY beatnote in IR found

Found the IR beatnote between PSL and Y end laser.

Since our goal was to find the beatnote ASAP to recover ALS, I ignored the fine details in alignment. I will revisit the setup to make some improvements in the near future.

1. Coupled the PSL IR beam leaking after the doubler into the fiber. We have only 10% coupling into the fiber at the PSL table right now (6mw); but this will be improved once I get a suitable translation stage for the telescope.

2. PSL IR --> PM980 fiber --->50-50 fiber beam splitter ---> 50-50 fiber beam combiner
  AUX Y ---> PM980 fiber ---> 50-50 fiber beam combiner

The output port of the fiber beam combiner is connected to the fiber coupled broadband RF PD.

3. The RF output of the PD when connected to a spectrum analyzer shows a beatnote of -50dBm. The small amplitude of the beatnote is due to the laser power being attenuated before coupling into the fiber to keep the PD safe.

Attached is photo of how the setup is put on the PSL table. We will put all the stuff in a box once the X setup is also in place.

Attachment 1: PSLsetup.jpg
PSLsetup.jpg
  10677   Thu Nov 6 10:18:12 2014 SteveUpdateGeneralfiber insulation in cable tray

Quote:

[Steve, Diego, Manasa]

Since the beatnotes have disappeared, I am taking this as a chance to put the FOL setup together hoping it might help us find them.

Two 70m long fibers now run along the length of the Y arm and reach the PSL table.

The fibers are running through armaflex insulating tubes on the cable racks. The excess length ~6m sits in its spool on the top of the PSL table enclosure.

Both the fibers were tested OK using the fiber fault locator. We had to remove the coupled end of the fiber from the mount and put it back in the process. So there is only 8mW of end laser power at the PSL table after this activity as opposed to ~13mW.  This will be recovered with some alignment tweaking.

After the activity I found that the ETMY wouldn't damp. I traced the problem to the ETMY SUS model not running in c1iscey. Restarting the models in c1iscey solved the problem.

 

 AP Armaflex  tube 7/8" ID X 1" wall insulation for the long fiber in wall mounted cable trays installed yesterday.

The 6 ft long sections are not glued. Cable tied into the tray pressed against one an other, so they are air tight. This will allow us adding more fibers later.

 Atm2: Fiber PSL ends  protection added on Friday.

 

Attachment 1: APT07810.jpg
APT07810.jpg
Attachment 2: fromYend.jpg
fromYend.jpg
  10678   Thu Nov 6 11:40:58 2014 SteveUpdateGeneralHe/Ne telescope

Liyuan is measuring the He/Ne telescopes in the Y arm between the tube and CES wall. He'll be here till 1pm

  10684   Fri Nov 7 10:29:56 2014 SteveUpdateGeneralHe/Ne telescope

Quote:

Liyuan is measuring the He/Ne telescopes in the Y arm between the tube and CES wall. He'll be here till 1pm

 Liyuan is continuing his measurement in the Y arm till noon today.

  10702   Wed Nov 12 15:14:09 2014 manasaUpdateGeneralX end AUX laser fiber setup

 I looked at the endtable for possible space to setup optics in order to couple the X end laser into a PM fiber.

Attached is the layout of where the setup will go and what are the existing stuff that will be moved.

ETMXtable.png

  10730   Fri Nov 21 11:41:24 2014 manasaUpdateGeneralX end fiber insulated and on cable tray

Quote:

Quote:

[Steve, Diego, Manasa]

Since the beatnotes have disappeared, I am taking this as a chance to put the FOL setup together hoping it might help us find them.

Two 70m long fibers now run along the length of the Y arm and reach the PSL table.

The fibers are running through armaflex insulating tubes on the cable racks. The excess length ~6m sits in its spool on the top of the PSL table enclosure.

Both the fibers were tested OK using the fiber fault locator. We had to remove the coupled end of the fiber from the mount and put it back in the process. So there is only 8mW of end laser power at the PSL table after this activity as opposed to ~13mW.  This will be recovered with some alignment tweaking.

After the activity I found that the ETMY wouldn't damp. I traced the problem to the ETMY SUS model not running in c1iscey. Restarting the models in c1iscey solved the problem.

 

 AP Armaflex  tube 7/8" ID X 1" wall insulation for the long fiber in wall mounted cable trays installed yesterday.

The 6 ft long sections are not glued. Cable tied into the tray pressed against one an other, so they are air tight. This will allow us adding more fibers later.

 Atm2: Fiber PSL ends  protection added on Friday.

 

[Steve, Manasa] 

Two 70m long fibers are now running through armaflex insulating tubes along the X arm on the cable racks. The excess length of the fiber sits in its spool on top of the PSL enclosure. 

Fibers were checked after this with the fiber fault locator (red laser) and found OK.

  10739   Mon Dec 1 15:41:38 2014 SteveUpdateGeneralX end fiber insulated and on cable tray

Quote:

Quote:

Quote:

[Steve, Diego, Manasa]

Since the beatnotes have disappeared, I am taking this as a chance to put the FOL setup together hoping it might help us find them.

Two 70m long fibers now run along the length of the Y arm and reach the PSL table.

The fibers are running through armaflex insulating tubes on the cable racks. The excess length ~6m sits in its spool on the top of the PSL table enclosure.

Both the fibers were tested OK using the fiber fault locator. We had to remove the coupled end of the fiber from the mount and put it back in the process. So there is only 8mW of end laser power at the PSL table after this activity as opposed to ~13mW.  This will be recovered with some alignment tweaking.

After the activity I found that the ETMY wouldn't damp. I traced the problem to the ETMY SUS model not running in c1iscey. Restarting the models in c1iscey solved the problem.

 

 AP Armaflex  tube 7/8" ID X 1" wall insulation for the long fiber in wall mounted cable trays installed yesterday.

The 6 ft long sections are not glued. Cable tied into the tray pressed against one an other, so they are air tight. This will allow us adding more fibers later.

 Atm2: Fiber PSL ends  protection added on Friday.

 

[Steve, Manasa] 

Two 70m long fibers are now running through armaflex insulating tubes along the X arm on the cable racks. The excess length of the fiber sits in its spool on top of the PSL enclosure. 

Fibers were checked after this with the fiber fault locator (red laser) and found OK.

 X-arm  AP Armaflex tube insulation is cable tightened into cable tray. Only turning 6 ft sections are taped together.

Remaining things to do: install ends protection tubing

  10740   Mon Dec 1 16:34:20 2014 JenneUpdateGeneralIFO wake-up

 

 After its' several days of rest, it is time to wake up the IFO. 

  • FSS temp was railed at +10, which was making the MC not want to lock.  Set it to zero, locked the MC, and ran the MC WFS relief scripts.
  • PMC trans is down to 0.686, so I'll probably want to tweak that up before I get too carried away for tonight. 
  • c1iscex computer was frozen, which I suspect is why Steve found ETMX tripped this morning.  Soft reboot, and we're back to normal.

With that, it's time for a new week of locking, and trying to catch up with the big kids at the sites.

  10742   Mon Dec 1 17:19:22 2014 JenneUpdateGeneralPMC align

[Diego, Jenne]

Tweaked up the input alignment to the PMC.  Now we're at 0.785.

  10758   Fri Dec 5 02:44:43 2014 JenneUpdateGeneralIFO alignment shenanigans

[Jenne, Q, Diego]

OMG, today sucked alignment-wise.  Like, wow. 

I think that the problem with the ASS is with the input pointing part of the system.  I found that if I disable the TTs for the Yarm (iin practice, the outputs are held at zero), I could run the Yarm ASS at full gain of 1, and it would do an awesome job.  The first time I did this, I by-hand optimized the TTs by running the test mass loops to make them follow the input pointing.  After that, I haven't touched the TT pointing at all, and we've just been running the test mass loops for the Yarm ASS.  The Xarm seems to not have this problem (or at least not as drastically), so I left it as it was, touching BS as well as ITMX and ITMY, although the gain still needs to be about 0.3.

I feel pretty good about the IFO alignment now, although it is slightly different than it has been.  The transmitted arm powers are higher than they were before I changed the ASS procedure, and there seems to be a little less power fluctuation with alignment.  Q points out that I don't have concrete evidence that this is a good alignment, but it feels right. 

It was a significant enough change that I had to go down to the Yend to realign the green to the new arm axis.  Xgreen we did with the remote PZTs.  I also realigned both of the beatnotes on the PSL table. 

While I was on the PSL table, I quickly touched up the PMC alignment.

The biggest problem, the one that sucked up more hours and energy than I'd like to admit, is ETMX's jumping.  So frustrating.  Sometimes it is time-coincident with engaging the LSC, sometimes not.  I thought that it might be because there are too many violin filters, but even if I turn off all violin filters to ETMX, it jumped a few times while the cavity was locked.  Sometimes it moves when the cavity is just locked and seems happy, sometimes it moves when nothing is resonating except for the green.  It takes a few minutes to recover the alignment enough to lock, and then it'll jump again a few minutes later.  I haven't gone down to squish the cables today, although I did it yesterday and that didn't seem to do anything. 

We had a few hours of time when it wasn't jumping, so we tried a few times to lock the IFO.  The last several times we have lost lock because the PRC loop rang up.  We measured the loop at low-ish arm powers, but it kept losing lock at higher powers before we could measure.  At least 3 times, the PRC lockloss took out CARM and DARM too.

Anyhow, it has been a long day of not accomplishing anything interesting, but hopefully the IFO will feel better tomorrow.

  10760   Sun Dec 7 13:11:57 2014 manasaSummaryGeneralFrequency Offset Locking - To Do List

Attached is the timeline for Frequency Offset Locking related activities. All activities will be done mostly in morning and early afternoon hours.

Attachment 1: FOLtodolist.pdf
FOLtodolist.pdf
  10765   Mon Dec 8 15:54:39 2014 manasaSummaryGeneralDec 8 - Check Frequency Counter module

Quote:

Attached is the timeline for Frequency Offset Locking related activities. All activities will be done mostly in morning and early afternoon hours.

[Diego, Manasa]

We looked into the configuration and settings that the frequency counters (FC) and Domenica (the R pi to which the FCs talk to) were left at . After poking around for a few hours, we were able to readout the FC output and see it on StripTool as well.

We have made a list of modifications that should be done on Domenica and to the readout scripts to make the FC module automated and user-friendly.

I will prepare a user manual that will go on the wiki once these changes are made.

 

  10766   Mon Dec 8 20:53:51 2014 diegoSummaryGeneralDec 8 - Check Frequency Counter module

Quote:

Quote:

Attached is the timeline for Frequency Offset Locking related activities. All activities will be done mostly in morning and early afternoon hours.

[Diego, Manasa]

We looked into the configuration and settings that the frequency counters (FC) and Domenica (the R pi to which the FCs talk to) were left at . After poking around for a few hours, we were able to readout the FC output and see it on StripTool as well.

We have made a list of modifications that should be done on Domenica and to the readout scripts to make the FC module automated and user-friendly.

I will prepare a user manual that will go on the wiki once these changes are made.

 

 OUTDATED: see elog 10779

 

I started working on the scripts/FOL directory (I did a backup before tampering around!):

  • I still need to make some serious polishing in the folder, and into the Raspberry Pi itself, in order to have a clean and understandable environment;
  • as of now, I created an single armFC.c program, which takes as arguments the device (/dev/hidraw0 for the X arm, and /dev/hidraw1 for the Y arm) and the value to write into the frequency counter (0x3 for initialization and 0x2 for actual use); hence, no more need for recompilation!
  • I improved the codetorun.py script (and gave the fellow a proper name, epics_channels.py) which handles the initialization AND the availability of the channels;
  • On the Raspberry Pi, I created two init scripts, /etc/init.d/epics_server.sh and /etc/init.d/epics_channels.sh, which start at the end of the boot process with default runlevels; the former starts the softIOc process (epics itself), while the latter executes the constantly running epics_channels.py script; as they are services, they can be started/stopped with the usual sudo /etc/init.d/NAME start|stop|restart

 

As a result, as soon as the Raspberry Pi completes its boot process, the two beatnote channels are immediately available.

 

  10767   Tue Dec 9 00:30:27 2014 manasaSummaryGeneralDec 9 - Elaborate to do list

Quote:

Attached is the timeline for Frequency Offset Locking related activities. All activities will be done mostly in morning and early afternoon hours.

Elaborate to do list:

1. The FC module should be mounted on the IOO rack. Domenica has to be powered up appropriately to the rack power supply.

2. The fiber chassis needs to be built. This will hold all the fiber components and will sit inside the PSL enclosure.
Fiber connectors and fiber couplers need to be installed in the chassis. Attached is the cartoon sketch of layout in the chassis.

3. User guide for FC module (work in progress)

Attachment 1: FOL_FiberChassis.pdf
FOL_FiberChassis.pdf
  10770   Tue Dec 9 16:06:46 2014 diegoSummaryGeneralDec 8 - Check Frequency Counter module

Quote:

Quote:

Quote:

Attached is the timeline for Frequency Offset Locking related activities. All activities will be done mostly in morning and early afternoon hours.

[Diego, Manasa]

We looked into the configuration and settings that the frequency counters (FC) and Domenica (the R pi to which the FCs talk to) were left at . After poking around for a few hours, we were able to readout the FC output and see it on StripTool as well.

We have made a list of modifications that should be done on Domenica and to the readout scripts to make the FC module automated and user-friendly.

I will prepare a user manual that will go on the wiki once these changes are made.

 

 I started working on the scripts/FOL directory (I did a backup before tampering around!):

  • I still need to make some serious polishing in the folder, and into the Raspberry Pi itself, in order to have a clean and understandable environment;
  • as of now, I created an single armFC.c program, which takes as arguments the device (/dev/hidraw0 for the X arm, and /dev/hidraw1 for the Y arm) and the value to write into the frequency counter (0x3 for initialization and 0x2 for actual use); hence, no more need for recompilation!
  • I improved the codetorun.py script (and gave the fellow a proper name, epics_channels.py) which handles the initialization AND the availability of the channels;
  • On the Raspberry Pi, I created two init scripts, /etc/init.d/epics_server.sh and /etc/init.d/epics_channels.sh, which start at the end of the boot process with default runlevels; the former starts the softIOc process (epics itself), while the latter executes the constantly running epics_channels.py script; as they are services, they can be started/stopped with the usual sudo /etc/init.d/NAME start|stop|restart

 

As a result, as soon as the Raspberry Pi completes its boot process, the two beatnote channels are immediately available.

 

 OUTDATED: see elog 10779

 

 Update and corrections:

 

  • I forgot to log that I added a udev rule in /etc/udev/rules.d/98-hidraw-permissions.rules in order to let the controls user access the devices without having to sudo all the time;
  • I updated the ~/.bashrc and /opt/epics/epics-euser-env.sh files to fix syntax errors and add some aliases we usually use;
  • since /etc/init.d/ doesn't support automatic respawn of processes, I purged the two scripts I did yesterday and added two lines to /etc/inittab. This works just as fine (I tried a couple of reboots to verify that) and the two processes now respawn automatically even if killed (and, I assume, if they die for any other reason)
  • Another thing I forgot: for the time being, during the cleanup, the Raspberry Pi works on the network share script directory. Once cleaning is done and everything is fixed, everything will run locally on the RPi, and the scripts/FOL directory on chiara will be used as backup/repository.
  10771   Tue Dec 9 16:07:16 2014 manasaSummaryGeneralDec 9 - FC module and fiber chassis

Quote:

Quote:

Attached is the timeline for Frequency Offset Locking related activities. All activities will be done mostly in morning and early afternoon hours.

Elaborate to do list:

1. The FC module should be mounted on the IOO rack. Domenica has to be powered up appropriately to the rack power supply.

2. The fiber chassis needs to be built. This will hold all the fiber components and will sit inside the PSL enclosure.
Fiber connectors and fiber couplers need to be installed in the chassis. Attached is the cartoon sketch of layout in the chassis.

3. User guide for FC module (work in progress)

1. FC module has been mounted on the IOO rack. The module gets it AC supply from the powerstrip already installed on the back side of the rack.

FCmodule.png

2. The fiber chassis has not been put together completely. We have still not received the front and back panels for the chassis; which is keeping me on hold. Diego is almost done with his housekeeping on Domenica. He will post an elog with all the details.

3. User guide for FC module (work in progress)

  10775   Wed Dec 10 16:12:29 2014 manasaSummaryGeneralDec 10 - PSL table

Quote:

Attached is the timeline for Frequency Offset Locking related activities. All activities will be done mostly in morning and early afternoon hours.

I was working around the PSL table today.

I wanted to modify the telescope that couples PSL light into the fiber; now that I have the translation stages for the lenses. I could not finish it as the locking work started earlier than usual this afternoon. I measured the out of loop noise for ALS error signals before I opened the PSL enclosure. X and Y beat notes were at -18dBm at 49.3MHz and -29.56dBm at 62.2MHz for this measurement. DTT data can be found in /users/manasa/data/141210/ALSoutLoop.xml; so there is reference to go back to in case of any damage done due to the work on the PSL table.

Also, I received the front and back panels for the Fiber chassis and put it together. Find photos (front panel and inside) of chassis in attachment. This will go inside the PSL enclosure tomorrow.

FiberMod_front.jpg    FOL_fiber.jpg

 

  10778   Thu Dec 11 10:08:10 2014 manasaUpdateGeneralIFO update

Status of IFO:

1. The X end slow computer is down. ETMX sliders and buttons on the ETMX suspension screens have gone white. I have disabled the ETMX oplev because it is largely misaligned in yaw. I am not poking it and leaving it as is for the time being.

2. The Y arm green alignment had drifted and GTRY was down to 0.15 . I tweaked the alignment using the last two steering mirrors and brought GTRY to 0.7 which gives a beat note of -14dBm.

  10780   Thu Dec 11 12:50:12 2014 manasaSummaryGeneralPSL table optical layout

 I assembled the telescope to couple PSL light into the fiber. The maximum coupling that I could obtain was 10mW out of 65mW (~15%).

I was expecting to achieve 80-90% coupling from my design estimates. It makes me wonder if the beam waist measurements made by Harry during summer were correct in the first place. I would like to go back and check the beam waist at the PSL table.

Also, we need a pair of 8m (~25 feet) long SMA cables to carry the RF signal from the beat PD on the PSL table to frequency counter module on the IOO rack.

Steve says that we had a spool of SMA cable and it was borrowed by someone a few months ago. Any updates on either who is holding it or if it has been used up already would help.


The X end slow computer was down this morning. So I used only the Y arm ALS to record the noise level for reference. DTT data for ALSY out of loop noise before opening PSL enclosure is saved in /users/manasa/data/141211/ALSYoutLoop.xml

  10787   Thu Dec 11 23:34:06 2014 manasaSummaryGeneralPSL table optical layout

Quote:

 I assembled the telescope to couple PSL light into the fiber. The maximum coupling that I could obtain was 10mW out of 65mW (~15%).

I was expecting to achieve 80-90% coupling from my design estimates. It makes me wonder if the beam waist measurements made by Harry during summer were correct in the first place. I would like to go back and check the beam waist at the PSL table.

Also, we need a pair of 8m (~25 feet) long SMA cables to carry the RF signal from the beat PD on the PSL table to frequency counter module on the IOO rack.

Steve says that we had a spool of SMA cable and it was borrowed by someone a few months ago. Any updates on either who is holding it or if it has been used up already would help.


The X end slow computer was down this morning. So I used only the Y arm ALS to record the noise level for reference. DTT data for ALSY out of loop noise before opening PSL enclosure is saved in /users/manasa/data/141211/ALSYoutLoop.xml

 I missed to elog this earlier. I have temporarily removed the DC photodiode for GTRY to install the fiber holder on the PSL table. So GTRY will not be seeing anything right now.

 

  10788   Fri Dec 12 02:30:25 2014 JenneSummaryGeneralPSL table optical layout

Quote:

 

 I missed to elog this earlier. I have temporarily removed the DC photodiode for GTRY to install the fiber holder on the PSL table. So GTRY will not be seeing anything right now.

 

 After some confusion, I discovered this a few hours ago.

  10791   Fri Dec 12 14:38:39 2014 manasaSummaryGeneralFrequency Offset Locking - To Do List (Revised)

Unfortunately the order placed for beam samplers last week did not go through. These will be used at the X and Y end tables to dump the unwanted light appropriately. Since they will not be here until Tuesday, I revised the timeline for FOL related activities accordingly.

Attachment 1: FOLtodolist.pdf
FOLtodolist.pdf
  10792   Fri Dec 12 15:19:04 2014 manasaSummaryGeneralDec 12 - PSL table

Quote:

Unfortunately the order placed for beam samplers last week did not go through. These will be used at the X and Y end tables to dump the unwanted light appropriately. Since they will not be here until Tuesday, I revised the timeline for FOL related activities accordingly.

I was working on the PSL table today. 

Since the rejected 1064nm light after the SHG crystal is not easily reachable to measure beam widths close to the waist, I put a lens f=300mm and measured the beam size around its focus. I used this data and redesigned the telescope using 'a la mode'.

I used a beam splitter to attenuate the beam directed towards the fiber. The reflected beam from BS has been dumped (I need to find a better beam dump than what is being used right now. 

I have only ~200uW at the input of the fiber coupler after the BS and 86uW at the output of the fiber (43% coupling)

I moved the GTRY DC photodiode and the lens in front of it to make space for the fiber coupler mount.

The layout on the PSL table right now is as shown below.

PSLtoFiber.png 

I have also put the fiber chassis inside the PSL enclosure on the rack. I moved the coherent spectrum analyser controller that is not being used to make space on the rack.

PSLfiberChassis.png

 
Attachment 2: PSLfiberChassis.png
PSLfiberChassis.png
  10808   Wed Dec 17 11:57:56 2014 manasaSummaryGeneralY arm optical layout

I was working around the PSL table and Y endtable today.

I modified the Y arm optical layout that couples the 1064nm light leaking from the SHG crystal into the fiber for frequency offset locking.

The ND filter that was used to attenuate the power coupled into the fiber has been replaced with a beam sampler (Thor labs BSF-10C). The reflected power after this optic is ~1.3mW and the trasmitted power has been dumped to a razor blade beam dump (~210mW).

Since we have a spare fiber running from the Y end  to the PSL table, I installed an FC/APC fiber connector on the PSL table to connect them and monitored the output power at the Y end itself. After setting up, I have ~620uW of Y arm light on the PSL table (~48% coupling).

During the course of the alignment, I lowered the power of the Y end NPRO and disengaged the ETMY oplev. These were reset after I closed the end table.

Attached is the out of loop noise measurement of the Y arm ALS error signal before (ref plots) and after.

 

Attachment 1: 58.png
58.png
  10831   Mon Dec 22 17:06:14 2014 manasaUpdateGeneralX end AUX laser fiber setup

Quote:

 I looked at the endtable for possible space to setup optics in order to couple the X end laser into a PM fiber.

Attached is the layout of where the setup will go and what are the existing stuff that will be moved.

ETMXtable.png

Since we will not be doing any major locking, I am taking this chance to move things on the X end table and install the fiber coupler.

The first steering mirror shown in the earlier elog will be a Y1 (HR mirror) and the second one will be a beam sampler (similar to the one installed at the Y endtable for the fiber setup). 

 

Configuration:

Doubler --> Y1 ---> Lens (f=12.5cm) ---> Beam sampler --->Fiber coupler

The fiber coupler mount will be installed in the green region to the right of the TRX camera. 

This work will involve moving around the TRX camera and the optic that brings the trans image on it.

Let me know if this work should not be done tomorrow morning for any reason.

  10834   Tue Dec 23 13:18:37 2014 manasaUpdateGeneralX end AUX laser fiber setup

Quote:

 

Since we will not be doing any major locking, I am taking this chance to move things on the X end table and install the fiber coupler.

The first steering mirror shown in the earlier elog will be a Y1 (HR mirror) and the second one will be a beam sampler (similar to the one installed at the Y endtable for the fiber setup). 

Configuration:

Doubler --> Y1 ---> Lens (f=12.5cm) ---> Beam sampler --->Fiber coupler

The fiber coupler mount will be installed in the green region to the right of the TRX camera. 

This work will involve moving around the TRX camera and the optic that brings the trans image on it.

Let me know if this work should not be done tomorrow morning for any reason.

I was working around the X endtable and PSL table today.

1. Y1 mirror, beam sampler and the fiber coupler have been installed.

2. Removed TRX camera temporarily. The camera will be put back on the table once we have the filter for 532nm that can go with it.

3. Removed an old fiber mount that was not being used from the table. 

4. Lowered the current for X end NPRO while working and put it back up at 2A before closing.

5. The fibers running from the X end to the PSL table are connected at an FC/APC connector on the PSL table. 

6. Found the HEPA left on high (probably from yesterday's work around the PSL table). I have brought it back down and left it that way.

I have not installed the coupling lens as yet owing to the space restrictions - not enough space for footprint of the lens. I have to revisit the telescope design again.

  10846   Mon Dec 29 21:30:25 2014 ranaUpdateGeneralrecovery
  1. Control room is at +66 F. Brrrr.
  2. Alignment of input beam into the IMC was wacky; locked on HOM.
  3. Re-aligned beam into the PMC first.
  4. Restarted mxstream for c1sus.
  5. Power cycled Martian router; all laptops were lost. Now better.
  6. Aligned launch beam from PSL to get onto the MCWFS better, MC is locking OK now. Moved MC SUS a little to get back to OSEM values from 6 days ago.
  7. Fixed LOCK_MC screen quad displays to be cooler.
  8. changed many of the ezcawrite calls in the mcup / mcdown to be 'caput -l' for more robustness. Still need ezcawrite for the binbary calls.
  9.  I didn't touch the mirrors on the MC REFL path, so we can still use that as a reference once the temperature returns to normal; the PSL room temp is down to 20C from 22 C a couple days ago.
  10. TRX values coming in to the LSC were frozen and the TRY_OUT16 was going to huge values even though camera flashes were reasonable. Tried restarting c1lsc model. No luck.
  11. Also tried shutdown -r now on c1lsc. No luck. Probably needs a RFM boot.
  12. Increased the FSS SLOW servo threshold to 9999 counts to avoid it running on some misaligned TEM01 mode locks. Increased the PID's I gain from 0.05 to 0.356 by tuning on some step responses as usual.
  13. By midnight the control room temperature is back around 71 F.
  10867   Wed Jan 7 12:15:17 2015 manasaUpdateGeneralNew RF cables

I was working around the PSL table this morning.

1. I have fibers running from the Y end and the PSL table to the Optical Fiber Module for Frequency Offset Locking. 

Y+PSL out power is ~200uW. From the transimpedance and responsivity specs of the RFPD (ThorLabs FPD310), we expect ~100uW or -10dBm RF power. I have not hooked up the RF output to a spectrum analyser to confirm this as yet.

2. Also, Steve and I ran RF cables (LMR-195A) from the PSL table to the FC module on the IOO rack.

 

  10871   Wed Jan 7 14:41:46 2015 SteveUpdateGeneralOphir pmeter filter found

Quote:

Quote:

Ophir power meter gets new filter with calibration. This is not cheap. It was the second time we lost it.

Filter leash is attached.

 Some one already took  off the filter and did not care to put it back on. This is carelessness!

Missing filter found. Labeled drawer OPHIR in control room - behind soldering station-  with spare battery and filter

  10873   Wed Jan 7 19:49:09 2015 manasaUpdateGeneralX end space issues

I have attached a photo of the ETMX table. The path of the 1064nm light rejected after the doubler and the green light are indicated for reference.

The fiber mount can only be mounted in the green space shown in the picture.

Calculating lens solutions for coupling the 1064nm light rejected after the doubler into the fiber, a lens of f=12.5cm should be placed at z=15.31cm (measured from the waist in the doubler crystal) gives the best ~80% coupling. This falls in the blue region where there is not enough space to mount a lens

The region marked in orange has enough room for a lens; but the lens solutions give a coupling <10% which means there will be light scattering everywhere.

I am open to any suggestions on how to go about this.

ETMXspace.png

  10874   Wed Jan 7 21:13:35 2015 ranaUpdateGeneralinane LSCoffsets script removed

Quote:

 A few things that I have neglected to ELOG yet:

  • scripts/offsets/LSCoffsets is a new script that uses ezcaservo to set FM offsets of our LSC PDs. It still warns about large changes, and lets you revert. It reads the FM gain to pick the right gain for the ezcaservo call. 

 We never, ever want to use ezcaservo to do this. IN fact, we twice have already deleted scripts where people have implemented these (sometimes) unstable servos. Also, since this change had never been committed to the SVN, I just deleted it and updated from the SVN to get back the script that doesn't use any servos.

I'm going to periodically delete locking scripts that are not committed to the SVN since anyone who is too lazy to use the SVN probably can't write code worth using.

  10880   Thu Jan 8 19:41:50 2015 ericqUpdateGeneralinane LSCoffsets script removed

The restored offset script used old tdsavg calls that our workstations can't do, and didn't include things like the transmon QPDs. I've written yet another offset script that uses cdsutils averaging to do the thing, and committed to the svn. 

  10883   Fri Jan 9 14:01:17 2015 manasaUpdateGeneralAUX Y + PSL beat note at 1064nm

I worked around the PSL table today.

The Y+PSL output from the optical fiber module for FOL was fed to the input of the Thorlabs FPD310
200uW of incident light on the RFPD gave an RF signal of -70dBm as measured on a spectrum analyzer.

I swapped the beam splitter along the PSL path so that the incident power on the RFPD is ~1.5mW (Maximum incident power that the PD can tolerate is ~2mW).
This RF signal generated was - 43dBm which is still small for the input to the frequency counter module.

I checked this with a function generator and found that the frequency counter requires around -25 to -30 dBm at the input.

I plan to use the Minicircuits ZFL-1000ln that is on the IOO rack but not being used (This was used for green beatnote amplification but is not required/used anymore) to amplify the RF signal to the frequency counter.
If anyone has any objections to using this amplifier for the frequency counter, let me know.

 

  10884   Fri Jan 9 14:13:02 2015 manasaUpdateGeneralALS noise at ~30Hz

Before starting to move things around the PSL table, I measured the ALS out of loop noise for reference. The noise spectrum showed excess noise around 30Hz.  The traces in blue were taken before I went in and those in red were taken after my work.

I also looked at the power spectrum of LSC-TRY_OUT to see if the noise is from the IR lock itself and there was nothing suspicious with it. 

Since the green transmission was 50% lower than the usual, I touched the steering mirrors for green at the Y end table to get a better transmission and beat signal. The noise still hasn't disappeared. 

I am not sure if this could be from our neigbors who have been running rock experiments since morning. We should check back to see if this noise disappears once they shut down.

DTT xml files are available in directory /users/manasa/data/150109/

Attachment 1: ALSYoutLoop.png
ALSYoutLoop.png
Attachment 2: LSC_TRY.png
LSC_TRY.png
  10893   Tue Jan 13 10:28:02 2015 manasaUpdateGeneralAUX Y + PSL beat note at 1064nm
Quote:
 

I plan to use the Minicircuits ZFL-1000ln that is on the IOO rack but not being used (This was used for green beatnote amplification but is not required/used anymore) to amplify the RF signal to the frequency counter.
If anyone has any objections to using this amplifier for the frequency counter, let me know.

The above mentioned amplifier has been used to amplify the input to the frequency counter. The frequency counter is now getting an input that it can read.

I have done an edit to the ALS medm screen and the PSL and AUX Y laser beat frequency is now readable.

  10894   Tue Jan 13 13:22:54 2015 JenneUpdateGeneralAUX Y + PSL beat note at 1064nm: needs work

I'm super excited about this new frequency readbacklaugh, but I'm not sure that it's reliable yetfrown.  Without touching any settings, the readback is currently saying 78.6MHz, and is changing slightly (as is the FSS Slow Temp), so something is working.  However, the beatnote as measured on the spectrum analyzer is 158.2MHz.  So, either the calibration or the tracking or something isn't quite finished being tuned yet.cheeky

It's going to be super awesome when we have this though!!cool

  10895   Tue Jan 13 14:01:20 2015 manasaUpdateGeneralAUX Y + PSL beat note at 1064nm: needs work
Quote:

I'm super excited about this new frequency readback, but I'm not sure that it's reliable yet.  Without touching any settings, the readback is currently saying 78.6MHz, and is changing slightly (as is the FSS Slow Temp), so something is working.  However, the beatnote as measured on the spectrum analyzer is 158.2MHz.  So, either the calibration or the tracking or something isn't quite finished being tuned yet.

It's going to be super awesome when we have this though!!

As Jenne pointed out, this is still not fully tuned. 

For example, I found today that the frequency counter requires more power at the input >= -20dBm to measure frequency inputs < 40 MHz. Since the RFPD gives ~ -40dBm at its output, the ~20dB gain amplifier will not be enough to measure low frequencies in case the beat power at the PD drops (which is very much possible when the alignment drifts or things move around on the PSL table).  So I am shopping for an RF amplifier with higher gain to replace the current one. In the meantime, I will test the PID loop for set point frequency > 40MHz.

I have also observed the frequency difference between the measured frequencies on FC and the spectrum analyzer. I am not sure where this comes from as yet. 

At this point, the FC readout is only reliable enough to find a beatnote that is lost on the spectrum analyzer.

  10918   Sat Jan 17 15:07:28 2015 manasaUpdateGeneralBeat note frequency discrepancy

I was around the PSL table and the X end table today.

X end table:

I was at the X end table making some distance measurements for the telescope to the fiber coupler. I have NOT moved anything as yet.

PSL table:

I wanted to get some data to look at the beat note frequency discrepancy between the green and IR. 

I tried making measurements using the spectrum analyzer at the PSL table but the MC was getting unlocked quite often with PSL enclosure open and HEPA on high. 

So I switched off the power supplies to the RFPDs (3 of them) on the PSL table and disconnected the Xmon input to the adder (at the IOO rack) which brings the green beat note signals to the conrol room. I connected the fiber RFPD output to the adder and took a bunch of measurements of the green and IR beat notes from the spectrum analyzer in the control room. I have NOT undone this setup assuming there are no locking plans for tonight and I will come back tomorrow. 

If anyone is planning to do some locking in the meantime, you can undo the connections keeping in mind to turn off the power to the RFPDs before you do so.

P.S. I walked in this morning to PSL FSS slow actuator at 0.89 and brought it down to zero before making measurements.
I also touched the steering mirrors that are part of the Y green beat note alignment while looking at the amplitude of the RF signal on the spectrum analyzer.

  10919   Mon Jan 19 11:03:32 2015 manasaUpdateGeneralRF connections to adder

RF connections to the beat note adder on the IOO rack have been undone and it should be good to proceed with any locking attempts.

Quote:

I was around the PSL table and the X end table today.

X end table:

I was at the X end table making some distance measurements for the telescope to the fiber coupler. I have NOT moved anything as yet.

PSL table:

I wanted to get some data to look at the beat note frequency discrepancy between the green and IR. 

I tried making measurements using the spectrum analyzer at the PSL table but the MC was getting unlocked quite often with PSL enclosure open and HEPA on high. 

So I switched off the power supplies to the RFPDs (3 of them) on the PSL table and disconnected the Xmon input to the adder (at the IOO rack) which brings the green beat note signals to the conrol room. I connected the fiber RFPD output to the adder and took a bunch of measurements of the green and IR beat notes from the spectrum analyzer in the control room. I have NOT undone this setup assuming there are no locking plans for tonight and I will come back tomorrow. 

If anyone is planning to do some locking in the meantime, you can undo the connections keeping in mind to turn off the power to the RFPDs before you do so.

P.S. I walked in this morning to PSL FSS slow actuator at 0.89 and brought it down to zero before making measurements.
I also touched the steering mirrors that are part of the Y green beat note alignment while looking at the amplitude of the RF signal on the spectrum analyzer.

 

  10955   Thu Jan 29 10:14:21 2015 manasaUpdateGeneralX end space issues

It is certain that we have space issues at the X end that has been preventing us from sticking in a lens to couple light into the fiber. 

The only way out is to install a platform on the table where we can mount the lens. I have attached the a photo of how things look like at the X end (attachment 1) and also a drawing of the platform that which can hold the lens (attachment 2). Additional support to the raised platform will be added depending on how much space we can clear up on the table by moving the clamping forks of the doubler.
Steve and I have been able to gather parts that can be put together into something similar to what is shown in the drawing. 

Proposed modifications to the X end table:

1. The side panels of the table enclosure will come out while putting in the new platform.

2. The clamping forks for the doubling crystal will be moved.

Let me know of any concerns about the proposed solution. 

Attachment 1: photo.png
photo.png
Attachment 2: drawing.png
drawing.png
  10956   Thu Jan 29 11:59:48 2015 manasaUpdateGeneralBeat note frequency discrepancy

Below is the set of plots comparing measurements for the green and IR beat notes frequencies. The measurements were made on the spectrum analyzer at the same time. So I have not taken measurement error into account. 
From the plots, the discrepancy is not very large.

Attachment 1:
Shows the two sets of measurements scaterred along y=x.

Attachment 2:
Since plot 1 shows the points tightly scattered to y=x, I plotted the difference between the two measurements against their mean to blow out the deviations.

I will do the same comparison using the frequency counter readout once we have RF amplifiers installed.

Attachment 1: Freq_compare1.png
Freq_compare1.png
Attachment 2: Freq_compare2.png
Freq_compare2.png
  10957   Thu Jan 29 16:14:10 2015 manasaUpdateGeneralUpdated to do list for FOL

Since there will be some work that supposedly will involve moving stuff on the table and racks; here is the updated to-do list for FOL.

  10964   Mon Feb 2 16:58:56 2015 manasaUpdateGeneralRF amplifier for ALS

Today I was around the IOO rack.

I shutdown the power to the beat PDs on the PSL table and disconnected the D sub 3w3 connector that was powering the RF amplifier panel on the IOO rack.

I moved the RF amplifier from the panel to a box that can go on the rack. The box will also hold the RF amplifiers that will be used for FOL. I have not completed putting in all the amplifiers. But the RF amplifier for ALS is in place and the box has been installed on the IOO rack for locking tonight. The power supply to the green beat PDs has been switched ON.

I took the out of loop noise measurements for ALS X and Y and the attachment is the screenshot of it (X and Y have rms of ~300Hz and ~400Hz).

I had to touch the Y end steering mirrors for green to get maximum GTRY before making thes measurments.

Attachment 1: ALSXY_outLoop.png
ALSXY_outLoop.png
  10970   Tue Feb 3 16:43:48 2015 manasaUpdateGeneralRF amplifier for ALS

I pulled out the RF amplifier box from the IOO rack again and added the new RF amplifiers for FOL. 

I replaced one of the decoupling capacitors of the ALS beat note RF amplifier ; the poloproylene capacitor with a ceramic capacitor (0.1uF) .

After putting back the box, I confirmed that we had a beat note. I did not get a chance to measure the ALS noise after putting back the box because the IFO was already occupied.

I will post a detailed elog of the components in the RF amplifier box once I am done with it (hopefully tomorrow)!

  10977   Wed Feb 4 21:05:24 2015 manasaUpdateGeneralRF amplifier for ALS

The components of the RF amplifier box are in place. The RF amplifier box has been mounted on the IOO rack and the front panel connections have been labeled. Attached is the photo of how things look in the inside for future reference.

Sometime in the next few days the box will be pulled out to replace the panel mount SMA barrels in the front with insulated ones.

Attachment 1: RFampBox.png
RFampBox.png
  10978   Wed Feb 4 21:09:43 2015 manasaUpdateGeneralX endtable work scheduled tomorrow

The X end fiber setup will be put together tomorrow morning. Let me know if there are any concerns.

Quote:

It is certain that we have space issues at the X end that has been preventing us from sticking in a lens to couple light into the fiber. 

The only way out is to install a platform on the table where we can mount the lens. I have attached the a photo of how things look like at the X end (attachment 1) and also a drawing of the platform that which can hold the lens (attachment 2). Additional support to the raised platform will be added depending on how much space we can clear up on the table by moving the clamping forks of the doubler.
Steve and I have been able to gather parts that can be put together into something similar to what is shown in the drawing. 

Proposed modifications to the X end table:

1. The side panels of the table enclosure will come out while putting in the new platform.

2. The clamping forks for the doubling crystal will be moved.

Let me know of any concerns about the proposed solution. 

 

  10981   Thu Feb 5 15:21:25 2015 manasaUpdateGeneralX endtable work

[EricG, Manasa]

We were at the X end today trying to couple AUX X light into the fiber. 

The proposed plan still did not give a good beampath. The last steering mirror before the fiber coupler was sticking out of the table enclosure. I tried a few other options and the maximum coupling that I could get was ~10%

I am working on plan C now; which would be to use fixed mount mirrors and steer the beam to the space created by Koji near the IR trans path and use a set of lenses instead of a single lens. I will elog more details after some modematching calculations.

We moved one of the clamps for the doubling crystal to make space. Also, the NPRO current was reduced during this work.

I reset things to how they were before I touched the table. I ensured that the green power was still the same (~3mW) after the doubler and that it could lock to the arm in TEM00.

  10985   Fri Feb 6 18:06:18 2015 manasaUpdateGeneralFiber Optic module for FOL

I pulled out the Fiber Optic Module for FOL from the rack inside the PSL table enclosure and modified it. The beat PDs were moved into the box to avoid breaking the fiber pigtail input to the PD.

The box has 3 input FC/APC connectors (PSL and AUX lasers) and 2 output FC/APC connectors (10% of the beatnote for the AUX lasers).

Attachment shows what is inside the box. The box will again go back on the rack inside the PSL enclosure.

Attachment 1: FOLfiberModule.png
FOLfiberModule.png
ELOG V3.1.3-